Cyclic guanosine monophosphate (cGMP) is an intracellular second messenger which acts as a signal molecule in various biochemical reaction processes in living body. So far it has been revealed that various physiological processes such as relaxation of vascular muscle cells, phototransduction in retina, epithelial electrolyte transport, bone growth, and neuronal activity are regulated by cGMP. Accordingly, if the synthesis, decomposition and localization of cGMP in living cells can be clarified, not only would the mechanism of cGMP at the cellular and tissue levels in the circulatory system, in the kidney and retina, in the olfactory and central nerves be understood, but would also provide hints for obtaining knowlege on substances such as phosphodiesterase inhibitors, which control intracellular cGMP levels in the cell.
Conventional methods of detecting and quantifying cGMP include radioimmunoassays using a radioisotope-labeled compound. However, this method involves disrupting cells and detecting the binding of cellular lysates to the labeled compound to analyze total cGMP levels, and did not realize the accuracy required in cell-biology and pharmaceutics.
Further, since such radioimmunoassay is a destructive measurement method, and further because the radioisotope-labeled compound is poor in stability and requires caution in handling, such conventional method could only be applied only to in vitro measurement of cGMP; in this respect, there was a limit to which the method could be applied.
The invention of the present application has been made in view of the circumstances as described above, and the object of the present invention is to solve the problem in the prior art and to provide a cGMP-visualizing probe, which enables the easy and highly accurate detection and quantification of cGMP, even in vivo, as well as a method of detecting and quantifying cGMP by using the same.